Method of treating lubricating distillates



Sept. 26, 1933. c. w. s'rRATl-TORD 1,927,853

METHOD QF TREATING LBRICATING DISTILLATES Filed Dec. 12. 1930 aow 6:4555

IN VEN TOR.

ATTO NEY.

am@ am? www@ Patented Sept. 26, 1933 UNITED STATES PATENT METHOD FTREATING LUBRICATING Drs'rrLLA'rEs Wall'e Application December 12, 19130Serial No. 501,758

Claims.

This invention relates to improvements in treating lubricating oildistillates, and refers more particularly to a method for dehydratingthe distillate and subsequently subjecting it to 5 treatment with acidand neutralizing agent.

The novelty of the invention lies principally in subjecting distillatesto a rapid and intimate contact with acid to eliminate undesirableconstituents, with a final treatment with a neutralizing agent such ascaustic soda or clay. The acid contacting stages may be with either weakor strong acid and by counterflow of the acid with the oil in thesuccessive stages of treatment. The system contemplates intermediatestages of centrifugal separation between the acid contacting steps. Bythe treatment, the distillate is first dehydrated in order to eliminatemoisture from the oil which is objectionable in the subsequent treatingstages. Also an accurate temperature control is maintained over the oilundergoing treatment in order that the distillate shall be supplied tothe acid contacting steps at an optimum temperature. The entire methodis in a closed system, the oil being passed therethrough continuously,thus affording considerably greater throughput rates than have beenpossible by the usual batch agitating methods which are at the presenttime common practice.

'Ihe single figure is a diagrammatic view of an apparatus adapted tocarry out the process.

Referring to the drawing, 1 and 2 are storage tanks, the former adistillate tank from which is supplied the lube distillate for thesystem. In the tank 2 is collected treated distillate as it isdischarged from the system. The numeral 3 indicates a heat exchanger, 4is a dehydrator, 5 and 6 are contactors, 7 and 8 centrifuges, 9, 10, 11,12, and 13 are centrifugal pumps. 14 is a blow case for weak acid, 15 ablow case for strong acid, while 16 and 17 are rate of flow blow caseswhich may be used with either the weak or strong acid as hereinafterexplained.

In operation, the lube distillate is withdrawn 45 from the tank 1through pipe 18 and is charged by means of the pump 9 through line 19and heat exchanger 3, thence through pipe 20 to the inlet 21 of thedehydrator 4. A heating or cooling medium is supplied to the exchanger 3through line 22 and discharged therefrom through pipe 23. Mounted on thetop of the dehydrator is a motor 24, driving a shaft 25 upon the lowerextremity of which is a circular dispersion plate 26 which is rotated athigh velocity by the mo- 5 tor. The liquid distillate, which has beenbrought to proper\temperature in the heat exchanger,

passes from the inlet pipe 21 down the vertical pipe 27 and isdischarged upon the upper surface of the rotating plate 26. This plateatomizes the distillate to present aA maximum evaporating surface of theinfeed oil. In the heat exchanger 3, oil is preferably brought to atemperature ranging from 150 to 300 F. according to the character andnature of the distillate being treated. Different types of oils requiredifferent temperatures in order to dehydrate and therefore a range oftemperatures must be provided to include lube distillates of differenttypes. The temperature to which the oil is raised in the heat exchangeris dependent not only upon the dehydration, but subsequent desirabletemperatures at which the oil is to be treated during the contactingstages. In other words, such temperatures must be maintained as toproduce viscosities best adapted to intimate contact with the acid inthe subsequent stages, as the viscosity of the oil is one of thedetermining fact-ors of the contact time and the ease and degree ofdispersion which can be produced not only in the evaporator 4 but alsoin the subsequent contacting and separation stages.

In the upper part of the dehydrator is a anged connection 27A, to whichis hooked up an apparatus for producing a reduced pressure within theevaporator. This apparatus includes a steam 5 vacuum booster pump 28,supplied with steam through a line 29. The discharge of the pump isconne'cted by a pipe 30 with a barometric condenser 31. Cooling water issupplied to the condenser through a line 32 and, on the discharge 90from the condenser, is a pump 33 which is supplied with steam throughthe line 34. Discharge from the pump 33 is through a pipe 35, throughwhich the energy steam, air and gas from the barometric condenser areexhausted or brought up to atmospheric pressure. The apparatus shown anddescribed for producing reduced pressure upon the dehydrator is ofcommon type and well known in this particular art.

In the bottom of the dehydrator is accumulated the anhydrous ordehydrated oil, and a liquid level control 36, connected to a valve 37interposed in a line 20, regulates the infeed of distillate charged tothe system. The accumulated anhydrous oil is discharged from thedehydrator through the pump 10, driven by a motor 38. Connected to thedischarge pipe 39 of the pump is a recirculation line 40, by means ofwhich the oil of the dehydrator may be circulated back into an infeedconnection 41 in order that complete dehydration is assured. A owindicator 42 and a valve 43 are interposed in the recirculating line 40,the former indicating the amount of recirculated liquid and the latterfurnishing a means for regulating the amount of recirculated distillate.

Distillate discharged from the pump 10 is directed through the line 39,through a meter 44, thence to the contactor 5. A temperature controldevice 45 is interposed in the line 39 and has a connection with a valve46 in the steam discharge pipe from the heat exchanger 3. Thistemperature control on the infeed for the rst contacting stage regulatesthe amount of heat supplied to the incoming distillate in order that itshall be charged to the rsvt contacting stage at an optimum temperaturefor the acid treatment.

Referring now to the acid supply, as suggested the blow case 14 containsweak acid and the blow case 15 strong acid. Compressed air through thepipe 47 supplies air pressure through connections 48 and 49to blow cases14 and 15, respectively and through connection 50 and lines 51 and52,7to blow cases 16 and 17; vents 53 and 54 are connected into lines 51and 52, and suitable Valves are interposed in all of the lines to permitaccurate control. Also there is a pressure regulator 55 in the line 47.Weak acid may be discharged from blow case 14 through pipe 56, thenceinto the rate of flow blow case through connection 57 by the airpressure imposed upon the acid charging system. The rate of flow of theacid may be read upon the gauge glass on blow case 16 as it isdischarged through pipe 58. A by-pass 59 is furnished around the blowcase. In the pipe 58 which directs the acid from blow case 16 to thecontactor 5 is a flow control device 60 regulating the valve 61. Thecontactors 5 and 6 shownv in the drawing are preferably of the typedisclosed in my Patent No. 1,736,018.

The acid and oil are intimately mixed in the contactor which constitutesthe initial step of acid treating. In place, of the weak acid, strongacid may be supplied to this initial contacting stage by withdrawingstrong acid from blow case 15 instead of 14 and directing itthrough-pipe 62, thence through cross-over line 63 into blow case 16 andout through the discharge pipe 58 to contactor 5.

From the initial contacting stage 5, whether strong or weak acid isused, the intimate mixture of oil and acid passes out throughthe line 64to the centrifuge 7. In this line 64 is a control valve 65 which isregulated by a flow control mechamsm 66 in the pipe 39. In other Words,the rate of infeed to the contactor is regulated by the dischargevalve.' In the centrifuge 7 the treated distillate is separated from theacid sludge, the distillate being discharged through the pipe 67 whilethe acid sludge is drawn off through a line 68 in which is a heatexchanger 69, adapted to facilitate handling thereof. This heatexchanger may be used either for heating or cooling. i, The distillatedischarged through the line 67 is picked up by the pump 11 and forcedthrough the pipe 70 and heat exchanger 71 into the second ,contactor 6.The heat exchanger 71 may be'used either to heat the oil or cool the oiland it is contemplated that the liquid introduced to the contactors maybe either heated or cooled prior to introduction thereto in order toprodce the optimum temperatures in the subsequent contacting or mixingstages. Either weak or strong acid is supplied to the contactor 6 fromblow cases 14 or 15. 1f weak acid is to be introduced, it 'is withdrawnfrom the blow case through pipe 56, thence through line 63 to linev72whichis a continuation of pipe 62. Through line 72 it can be introducedto blow case 17 through pipe 73, or bypassed around the blow casedirectly into the contactor. Pipe 74 connects the blow case 17 'with thelower end of pipe 72. Above the contactor is flow control mechanism 75regulating the valve 76 and above each of the contactors are manuallyoperated valves 77 and 78. Strong acid may be supplied to the contactorthrough line 62 from blow case 15 and thence through the metering blowcase 17 or through the by-pass directly to the contactor. The mixed oiland acid is discharged from contactor 6 through line 79 and isintroduced to centrifuge' 8 where separation is again made; the acidsludge or spent acid is discharged through pipe 80, in which isinterposed a heat exchanger 8l, thence to the pump l2, which directs thespent acid or acid sludge into the line 82 to be returned to thepreceding contacting stage or contactor 5, through pipe 83. Wherecounterow operation of the acid'and oil is not desired, the acid sludgewithdrawn from the centrifuge 8 may be diverted from the system throughpipe 84 by manipulation of the valves in lines 82 and 83. The distillaterecovered from the second centrifuge 8 is withdrawn through pipe 85 andis picked up by the pump 13 and forced through line 86 through themetering device 87, into a final neutralizing stage V88 where ,the oilmay be given either a treatment with' caustic soda or with clay. Wherethe neutralizing stage is a soda treatment stage, preferably a contactorand separator are used. The separator may be either a centrifuge or asettling device such as is shown in my issued Patent 1,736,018. Wherethe neutralizing stage is obtained with clay, a contactor and lter arethe preferred apparatus. The treated distillate from the neutralizingstage is directed through a line 89 to the distillate storage tank 2.

Valves have been interposed in the lines throughout4 the system but havebeen omitted from the explanation in the interest of simplicity.4

kAlso it will be noted that by-passing lines are furstages shown, thesystem may be supplemented with additional stages which shall beconnected up in such a manner that weak or strong acid inay be suppliedin, order to/obtain a once through operation of either type of acid withthe addiltional contacting stages. These additional stages also shouldbe connectedinto the system in order that counterflow operation of theacid and oil could be. used throughout thesystem.

. As suggested heretofore, different lube distillates have optimumtreating temperatures due to variations in viscosity. It will beappreciated that viscosity is a salient consideration in a system ofthis type in order to produce complete dehydration and to raise the oilto a temperature at which proper treating with acid can be effected inthe contacting stages. Control of viscosity is important in order thatthe oil is satisfactorily treated within the time and power range of thesystem.

Fundamentally the system is entirely closed in order that it shall notbe affected by air and lmoisture conditions and the oil as it is chargedto the acid treating steps is substantially anhydrous, thus eliminatingdifficulties heretofore encountered with usual methods wherein themoisture in the oil affects acid sludge obtained after acid contacting.A reduced pressure in the evaporator is important to avoid excessivetemperature in the subsequent treating stage.

The system contemplates the use of weak or strong acid charged to theseparate stages of contacting accompanied by immediate diversion of thesludge from the system from each of the contacting steps. Itcontemplates also the use of a counterow operation in which weak orstrong acid is charged to the final contacting stage and passed in anopposed direction to the oil in the preceding contacting stages to beiinally diverted from the system from the initial contacting stage.

Qptional methods for neutralization are suggested and contemplated inthefinal stage 88. The combination of dehydration and temperature controlare important factors in procuring optimum viscosity, a condition of thedistillate best adapted for the acid treating steps. The viscosity ofthe oil is obviously a determining factor Aon ease and degree ofdispersion, both in the dehydrator and' in the contacting and separatingsteps. It is also a factor in the contact which is necessary forsatisfactory treatment of the oil.

I claim as my invention:

1. A method of treating lubricating distillates comprising the steps ofheating the oil, dehydrating it in a stage of reduced pressure,subjecting the oil to acid treatment in a plurality of contacting'stages accompanied by intermediate stages of centrifugal separation,followed by a final neutralizing treatment, and regulating the heatsupplied to the oil by the temperature of the oil charged to the initialacid treating stage.

2. A method of treating lubricating distillates comprising the steps ofheating the oil, dehydrating it in a stage of reduced pressure,subjecting the oil to acid treatment in a plurality of contacting stagesaccompanied by intermediate stages of centrifugal separation. followedby a final neutralizing treatment, and regulating the heat supplied tothe oil by the temperature of the oil charged to the initial acidtreating stage to produce dehydration, and optimum temperatures andviscosity conditions in the subsequent acid treating stages.

3. A method of treating lubricating distillates comprising the steps ofheating the oil, dehydrating it in a stage of reduced pressure,subjecting the oil to acid treatment in a plurality of contacting stagesaccompanied by intermediate stages of centrifugal separation, followedby a nal neutralizing treatment, and regulating the heat supplied to theoil by the temperature of the oil charged to the initial acid treatingstage, creating a local cyclic movement of the oil through thedehydrating stage to eect complete dehydration of the oil and permitaccurate and constant metering of the oil charged to the subsequent acidtreating stages.

` 4. A method of treating lubricating distillates comprising the stepsof heating the oil, dehydrating it in a stage of reduced pressurewherein the oil is dispersed to offer increased evaporating surface,subjecting the oil to acid treatment in a plurality of contacting stagesaccompanied by intermediate stages of centrifugal separation wherein theoil is passed in counterflow relation to the acid, followed by a finalneutralizing treatment, regulating the heat supplied to the oil by thetemperature of the oil charged to the initial acid treating stage.

5. A method of treating lubricating distillates comprising the steps ofheating the oil, dehydrating it in a stage of reduced pressure whereinthe oil is dispersed to offer increased evaporating surface, subjectingthe oil to an acid treatment in a plurality of contacting stagesaccompanied by intermediate stages of centrifugal separation, utilizingacids of different concentration in the respective contacting stages,subjecting the oil to a final neutralizing treatment, regulating theheat supplied to the oil by the temperature of the oil charged to theinitial acid treatment stage.

CHARLES WALCO'II'I` STRATFORD.

